While effective smoking cessation treatments exist, there is significant room for improvement. Even with the current standard counseling plus pharmacotherapy, an average of 81 percent to 86 percent of smokers will relapse to smoking. Little attention has been placed on testing new behavioral cessation treatments aimed at increasing quit rates. To address this critical need, the current study will test the effectiveness of a newly emerging counseling approach called Acceptance & Commitment Therapy (ACT). To date, three trials of ACT for smoking cessation have been conducted. Overall, these three trials have been promising with the ACT intervention groups obtaining about 30 percent to 35 percent quit rates at 12 months post intervention-about double the 14 percent to 19 percent quit rates at 12 months post intervention for CBT plus NRT. The results of each trial suggest that ACT is a promising counseling approach for smoking cessation. However, only one study compared ACT with standard cognitive behavioral counseling (CBT) and all three studies had major methodological limitations which make it difficult to draw definitive conclusions about ACT's effectiveness for smoking cessation. Accordingly, a well-powered randomized trial comparing ACT with CBT for smoking cessation is now needed. In addition to providing important information about the comparative effectiveness of these treatment approaches, such a trial would allow for testing of the underlying processes through which ACT is hypothesized to exert its impact. The overall aim of this 5-year project is to capitalize on the strong theoretical and promising empirical evidence for ACT as an intervention for smoking cessation by comparing the effectiveness of group-delivered ACT against standard CBT counseling when both are offered with nicotine replacement therapy (NRT) and delivered within a real world health care setting. The specific aims of this research are to: (1) Determine the effectiveness of ACT as a group-delivered smoking cessation intervention plus NRT patch as compared to standard care group-delivered CBT counseling plus NRT patch; (2) Determine if the effectiveness of ACT is, as hypothesized, mediated by two key theory-based factors: (a) acceptance of internal cues to smoke (sensations, emotions, and thoughts) and (b) commitment to quitting smoking despite internal cues to smoke. The secondary aim will be to explore the role of quit attempts, alcohol use, gender, and recent depressive and anxiety symptoms as moderators of the ACT intervention effect. The proposed intervention is highly innovative and addresses an important research need - evaluating novel forms of counseling to enhance smoking cessation outcomes. If effective, the proposed intervention stands to make a significant impact and the ACT protocol could be disseminated in other clinical settings around the U.S.